1. Field of the Invention.
This invention relates to an apparatus for forming a pressure seal at the seam of two conduits and, more particularly, to such a device which incorporates a single pair of threaded members which cooperatively provide a generally axial uniform sealing force around the entire perimeter of the port column and male flange of a nuclear reactor instrumentation port.
2. Background Information.
The port column and male flange of a nuclear reactor instrumentation port, are two generally tubular members which are sized to cooperate in a telescoping manner.
The port column defines, near one end, a conical sealing flange against which is disposed a conical gasket. When placed in contact, under force, with a cooperating conical sealing recess in f the male flange, the conical sealing flange and gasket seal the seam between the port column and male flange thereby resisting the passage of fluid through the seam.
Located within the port column and male flange are electrical conductors which are necessary in the operation of the nuclear reactor As pressurized radioactive fluid is contained within the nuclear reactor it is critical that the seam between the port column and male flange be properly sealed to prevent the escape of radioactive material from the reactor. The conical seals are designed to provide such sealing action when the port column and male flange are pushed or clamped so that they are axially extended relative to one another.
The current apparatus to provide such clamping action incorporates the use of six separate jackscrews, each of which must be separately torqued in stages to provide the necessary axial clamping force around the entire perimeter of the port column and male flange. The jackscrews are disposed circumferentially around the perimeter of the port column and male flange through an annular ring called a jackscrew plate.
The base of each jackscrew is in contact with an annular shoulder which is formed in the male flange and the jackscrew plate is in contact with a protruding portion of a split ring which is disposed within an annular recess formed in the port column. The threads of each jackscrew cooperate with threads formed in circumferentially spaced holes formed in the jackscrew plate.
To axially extend the port column from the male flange, thereby creating the necessary clamping force and resultant seal, the jackscrews are rotated thereby moving the jackscrew plate in a direction away from the male flange and base of the jackscrews. The base of the jackscrews, thus, apply a force to the male flange while the jackscrew plate applies an equal and oppositely directed force to the split ring which, in turn, is transmitted to the port column.
Problems exist with this arrangement. Each jackscrew may be turned, individually, only a few turns before resistance in turning is encountered due to the remaining stationary jackscrews holding the jackscrew plate in place. Therefore, the remaining five jackscrews must each, individually, be turned a small number of turns to move the jackscrew plate evenly. The process must be repeated several times until the jackscrews and the jackscrew plate apply the necessary force between the port column and male flange. That creates problems.
First, the requirement that each jackscrew be rotated individually only a few turns at a time is both tedious and time consuming as each jackscrew must be turned individually six or more separate times, each time alternating with the other five jackscrews. Such a time consuming sealing process is undesirable in the environment in which the device is used. Second, if a person is careless in rotating the jackscrews, the jackscrews can be bent. That necessitates replacement of the jackscrews and, if the threads of the jackscrew plate have also been damaged, then the entire jackscrew plate may require replacement. Third, if the jackscrews are not finally torqued generally evenly, an unequal sealing force will occur around the port column and male flange perimeter which may possibly compromise the effectiveness of the seal.
There remains, therefore, a real need for an apparatus which is capable of axially extending on clamping the port column from the male flange, of a nuclear reactor instrumentation port, which eliminates the problems of the currently used apparatus.